Catalytic Polymerization of n-Doped Poly(benzodifurandione) (n-PBDF) Using Parts Per Million (ppm) Levels of...

The recent discovery of highly conductive, solution-processable, n-doped poly(benzodifurandione) (n-PBDF) has significantly pushed the boundaries of organic electronics. However, to maximize its practical impact, an efficient, scalable and cost-effective synthetic method is essential. Initially, n-PBDF was synthesized via duroquinone-mediated or copper-catalyzed polymerizations, but these methods required prolonged dialysis, limiting their scalability. Our recent SeO₂-catalyzed polymerization improved efficiency but still necessitated centrifugation and filtration to remove solid selenium byproducts. In this work, we introduce a highly efficient molybdenum trioxide (MoO₃)-catalyzed polymerization of n-PBDF. Remarkably, MoO₃ at parts-per-million (ppm) concentrations achieves near-quantitative monomer conversion (>99% by NMR), eliminating the need for purification. Kinetic studies demonstrate that this polymerization follows a chain-growth mechanism, enabling the synthesis of high-quality n-PBDF polymers with controlled particle sizes and block copolymers. Mechanistic investigations reveal that MoO₃ mediates an oxidative pathway involving dimethyl sulfoxide (DMSO), with dimethyl sulfide (DMS) identified as the reduction product. This innovation not only provides a scalable, low-cost route to high-quality n-PBDF but also unlocks new synthetic opportunities, significantly expanding the synthetic toolbox for functional polymers.